CA1263245A - Process for the launching from the mainland of large- size submarine pipelines, in particular for intake installations - Google Patents
Process for the launching from the mainland of large- size submarine pipelines, in particular for intake installationsInfo
- Publication number
- CA1263245A CA1263245A CA000524676A CA524676A CA1263245A CA 1263245 A CA1263245 A CA 1263245A CA 000524676 A CA000524676 A CA 000524676A CA 524676 A CA524676 A CA 524676A CA 1263245 A CA1263245 A CA 1263245A
- Authority
- CA
- Canada
- Prior art keywords
- pipeline
- launch
- water
- cylindrical volumes
- pipelines
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000009434 installation Methods 0.000 title abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000000926 separation method Methods 0.000 claims abstract description 13
- 239000012530 fluid Substances 0.000 claims description 4
- 238000007598 dipping method Methods 0.000 claims description 3
- 238000007667 floating Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- 230000000254 damaging effect Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 240000006108 Allium ampeloprasum Species 0.000 description 1
- 241001474374 Blennius Species 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006353 environmental stress Effects 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 235000015170 shellfish Nutrition 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
- F16L1/12—Laying or reclaiming pipes on or under water
- F16L1/16—Laying or reclaiming pipes on or under water on the bottom
- F16L1/165—Laying or reclaiming pipes on or under water on the bottom by towing the pipe on or near the bottom
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Pipeline Systems (AREA)
- Cleaning In General (AREA)
- Pipe Accessories (AREA)
- Underground Structures, Protecting, Testing And Restoring Foundations (AREA)
- Underground Or Underwater Handling Of Building Materials (AREA)
- Sewage (AREA)
Abstract
"PROCESS FOR THE LAUNCHING FROM THE MAINLAND OF LARGE-SIZE SUBMARINE PIPELINES, IN PARTICULAR FOR INTAKE
INSTALLATIONS"
Abstract Process for the launching from the mainland of large-size submarine pipelines, in particular for intake installations, consisting in subdividing the inner volume of the pipeline in a plurality of cylindrical volumes by means of a plurality of removable separation septa;
connecting such cylindrical volumes with removable connections, to feed ballast water and compressed air from the outside of the pipeline, flooding the cylindrical volumes up to confer the desired negative buoyancy (water weight) to the pipeline; launching the pipeline by draught from the sea end; removing the removable service connections and separation septa, after the end of the launch operation.
INSTALLATIONS"
Abstract Process for the launching from the mainland of large-size submarine pipelines, in particular for intake installations, consisting in subdividing the inner volume of the pipeline in a plurality of cylindrical volumes by means of a plurality of removable separation septa;
connecting such cylindrical volumes with removable connections, to feed ballast water and compressed air from the outside of the pipeline, flooding the cylindrical volumes up to confer the desired negative buoyancy (water weight) to the pipeline; launching the pipeline by draught from the sea end; removing the removable service connections and separation septa, after the end of the launch operation.
Description
~ ~, ,3~ d~ii "PROCESS FOR THE LAUNCHING FROM THE MAINLAND OF LARGE-SIZE SU~MARINE PIPELINES, IN PARTICULAR FO~ INTAKE
INSTALLATIONS"
The present invention relates to the launching of large-size submarine pipelines by starting ~rom the mainland, on which they are previously assembled from shorter sections.
More particularly, such launching operations relate ~o the Laying of pipelines ~o cross stretches of fresh water or of sea water of small size, of water streams, or for the water ;ntakes for industrial works, the assemblage of which is carried out on the mainland, the assembled pipeline being then launched by being pulled from its offshore end, by means of an anchored pontoon, or by a winch with offshore return.
According to the launch technology, the pipeline section assembled on the mainland must be launched while be;ng equipped with suitable weights, so that the structure being launched has an overall specific gravity slightly higher than of the water it has to be launched inO
Such a specific gravity slightLy higher than of the Z0 medium the pipeline is launched in, allows ~he pipeline section to maintain, while it is being laid, a residual water we;ght, which keeps it adherent to the profile of the water stretch bottom and ;n the assigned position, by counteracting the thrust applied to it by possible streams, wavy motions or other environmental stresses, but such that, at the same time, the pipeline being launched does not show a too high friction resistance deriving from the launching motion relatively to the ~3~
bottom - and opposed to i~.
With the equipment for pulling the pipeline being the same, launched can be preassembled pipeline sections which are the longer, the lower the "specific" resistance offered by the pipeline~
According to the technique of the pr;or artO various modalities are presently applied for increasing the ~eight of the pipeline. Such modalities are now described briefly.
The most widespread launching method consists in ~elding onto the offshore end of the pipeline which is being launched, a blind component, or either conical or rounded shape, provided with means for the anchDring of the pulling cables, and which allows the pipeline to be t;ghtly sealed; ma;ntaining empty the pipeline, and increasing its weight by applying onto its outer surface a coating with cement mortars of various compositions, and provided with reinforcing elements ("concrete spraying" process).
The increase in ~eight obtained by means of the concrete spraying method results very inaccurate, inasmuch as practically obta;ning, at the end of the operation, the theoretical thickness - and hence the theoretical weight - of the material applied onto the pipel;ne, in particular, in case of large-diameter pipelines, is difficult. Furthermore, the concrete spraying process results expensive, both because of ~he need for large amounts of the required materials, and due to the long process;ng times re~u;red for their appl;cation, their hardening~ and the;r necessary ageing~
before ;t being possible th~ p;pel;ne to be slid on the bottom.
Another draught method for increasing the weight of the pipeline consists in applying, to the mouth of the end of the pipeline being launched, the blind component, as of the former method, and in then ~loodin~ the pipeline, the specific weight of this latter being maintained at the desired value by applying, along the length of the pipel;ne, a plurality of floating bodies, which support it.
According to a more common variant of such a method, the floating bodies are applied externally to the pipeline, at discrete intervals in the axial directions, by means of suitable fastening means (brackets, ropes, chains, etc.)~ At the end of the launch, the floating bodies and their fastening means are removed and recovered. Such a variant shows the drawbacks deriving from the fact that, especially during the initial portion of their run together with the pipeline, the buoys, as ~ell as the fastening means, undergo creepings, and damaging.
In addition to the costs deriving from the possible replace0ent and repair of such buoys and of the fastening means for them, such damagings oblige the launching operations to be stopped to the purpose of repairing the
INSTALLATIONS"
The present invention relates to the launching of large-size submarine pipelines by starting ~rom the mainland, on which they are previously assembled from shorter sections.
More particularly, such launching operations relate ~o the Laying of pipelines ~o cross stretches of fresh water or of sea water of small size, of water streams, or for the water ;ntakes for industrial works, the assemblage of which is carried out on the mainland, the assembled pipeline being then launched by being pulled from its offshore end, by means of an anchored pontoon, or by a winch with offshore return.
According to the launch technology, the pipeline section assembled on the mainland must be launched while be;ng equipped with suitable weights, so that the structure being launched has an overall specific gravity slightly higher than of the water it has to be launched inO
Such a specific gravity slightLy higher than of the Z0 medium the pipeline is launched in, allows ~he pipeline section to maintain, while it is being laid, a residual water we;ght, which keeps it adherent to the profile of the water stretch bottom and ;n the assigned position, by counteracting the thrust applied to it by possible streams, wavy motions or other environmental stresses, but such that, at the same time, the pipeline being launched does not show a too high friction resistance deriving from the launching motion relatively to the ~3~
bottom - and opposed to i~.
With the equipment for pulling the pipeline being the same, launched can be preassembled pipeline sections which are the longer, the lower the "specific" resistance offered by the pipeline~
According to the technique of the pr;or artO various modalities are presently applied for increasing the ~eight of the pipeline. Such modalities are now described briefly.
The most widespread launching method consists in ~elding onto the offshore end of the pipeline which is being launched, a blind component, or either conical or rounded shape, provided with means for the anchDring of the pulling cables, and which allows the pipeline to be t;ghtly sealed; ma;ntaining empty the pipeline, and increasing its weight by applying onto its outer surface a coating with cement mortars of various compositions, and provided with reinforcing elements ("concrete spraying" process).
The increase in ~eight obtained by means of the concrete spraying method results very inaccurate, inasmuch as practically obta;ning, at the end of the operation, the theoretical thickness - and hence the theoretical weight - of the material applied onto the pipel;ne, in particular, in case of large-diameter pipelines, is difficult. Furthermore, the concrete spraying process results expensive, both because of ~he need for large amounts of the required materials, and due to the long process;ng times re~u;red for their appl;cation, their hardening~ and the;r necessary ageing~
before ;t being possible th~ p;pel;ne to be slid on the bottom.
Another draught method for increasing the weight of the pipeline consists in applying, to the mouth of the end of the pipeline being launched, the blind component, as of the former method, and in then ~loodin~ the pipeline, the specific weight of this latter being maintained at the desired value by applying, along the length of the pipel;ne, a plurality of floating bodies, which support it.
According to a more common variant of such a method, the floating bodies are applied externally to the pipeline, at discrete intervals in the axial directions, by means of suitable fastening means (brackets, ropes, chains, etc.)~ At the end of the launch, the floating bodies and their fastening means are removed and recovered. Such a variant shows the drawbacks deriving from the fact that, especially during the initial portion of their run together with the pipeline, the buoys, as ~ell as the fastening means, undergo creepings, and damaging.
In addition to the costs deriving from the possible replace0ent and repair of such buoys and of the fastening means for them, such damagings oblige the launching operations to be stopped to the purpose of repairing the
2~ damaged buoy, thus slackening the whole installa~ion process.
` In order to obviate such drawbacks, according to an improved variant of such a method, float;ng bodies of long shape, placed inside the pipeline, are adopted.
Such a contrivance overcomes the drawbacks characterizing the former variant, but causes notable ;
~ ~ J~
~omplications, bo~h as regards the proper positioning of the floating bodies inside the pipeline, and the procedure for recovering them, at the end of the launch~
During the launching operation9 the buoys used to 5 attain the desired residual weight of the water-filled pipeline, applied both inside the pipeline, and externally to it, are dragged to increasing depths.
This fact leads to a considerable drawback for the buoys constituted by such pneumatic bodies, as balloons or cylinders filled with compressed air, which are the buoys endowed ~ith the best handling and economy of use characteristics.
Such pneumatic bodies, placed at an increasing depth, shrink under the effect due to the increase in the outer pressure; to restore the;r value of positive upwards - buoyancy, such bodies have to be inflated, as the launch being discussed brings them to increasing depths, to the purpose of bringing them back to their initial value.
As an alternative, it is also possible to change the length of the connection between the pipeline being launched and the outer buoys, so to keep these latter at a substantially constant depth.
Both of these solutions result complex.
The adoption of rigid buoys, able to withstand the outer pressurey obliges to resort to rather heavy, poorly handeable metal structures.
Both of ~he procedures of application of the buoys dur;ng the launch, and the procedure for the recovery of the buoys, at ~he end o~ the launch, for them to be used in another site, result complex~
~3~
- 5 ~
The techniques exposed up to here suffer moreover from the drawback tha-t the increase in weight conferred to the pipeline results fixed a priori, and cannot be easily adjusted or modified during the laying, should, e.g., the unevennesses of the bottom, or changes in the ambient conditions, require the residual weight of the whole pipeline, or of a portion thereof, to be changed.
The laying process according to the present invention allows the weight of a pre-assembled pipeline to be increased with precision, to the desired weight value for the pipeline to be launched from the mainland, and said weight to be varied, both over time and along the various sections of the pipeline, as well as said launch to be carried out easily and with economies both of time and of materials.
According to the present invention there is provided a process for the launching of large-size submarine pipelines asse~bled on the mainland and then launched by draught from the water side, characterized in that the launch steps are so arranged:
- subdivision of the inner volume of the pipeline into a plurality of cylindrical volumes, by positioning a plurality of removable separation septa;
- connection of such cylindrical volumes to the outside by means of service connections, at least one of which for the supply and the discharge of ballast water, and at least one for the supply of compressed air inside the top portion of said cylindrical volumes;
- flooding of the cylindrical volumes, normally in correspondence of their dipping into the water stretch wherein the launch is carried out, up to obtain, for the dipped pipeline section, a desired residual weight, the possible ballast excess being expelled by being displaced by ~,"
~, 5a -compressed air;
- con-tinuation and completion of the pipeline launch, by adjusting, by means of the supply or of the discharge of ballast water, the residual weight to be conferred to the pipeline sections already laid in the dep~h;
- completely flooding of the pipeline and removal of the connections and of the separation septa, at the end of the launch.
Such a process of the invention shall be disclosed, by referring to the figure, in the specific application to the lauch of large-size pipelines destined to water intake installations for industrial plants.
However, the following disclosure should not be considered as being limitative of the application scope of the present invention, in that this latter can be used also for large-size pipelines for different uses.
Such pipelines are characterized indeed by very large flowrates, and thus large diameters - up to more than 2,500 mm - as well as by low operating pressure drops, and, consequently, by very limited wall thicknesses - comprised within the range of from 15 to 30 mm - which render such pipelines very dilicate during the launch operations, should they undergo stresses not uniformly distributed lengthwise to ~ ~
.~ _ ..'.~f,.~
According to the coas~al site the water intake units for industrial plants are being installed at, these latter have a length which is usually compr;sed within the range of up to 3 km~ and lay at such a depth as to guarantee the ;ntake of clean water, at a substantially constant temperature during the medium term; and, however, not influenced by the day temperature excursions. According to the site, and the bottoms, such a depth is comprised, in the most frequent cases, within the range of from 10 to 15 metres~
By starting from the intake end, equipped with various grids and protections9 to prevent foreign bodies of discrete dimensions to enter the pipeline, this latter extends up to the mainland, wherein the industrial works are instaLled. In many instances, in the intake unit, in a sea environment, also means are installed for the supply, the metering and the distribution of aclditives to preventr or, at least, limit, the growth of colonies of marine fLora and/or fauna - seaweeds, shellfish and the like - which may occlude the pipeline, even completely, within a short time~ rendering it useless.
The pipelines of the intake installations are provided, at discrete lengths~ with large manholes, whiçh allow skin-divers, provided ~ith aqualungs~ to enter the inner of the pipeline, to period;cally inspec~ the pipeline and eventually service it.
The Length of such sectionsp between the manholes, is generally comprised within the ~ange of from 50 to 120 m, and the manhole has an inner diameter of from 1200 to 1800 mm, which allows the skin divers and their equ;pment to easiiy enter the pipelines.
In the hereto attached figure, the pipeline 1, provided with the manholes 2, which is made advance on the bottom 3, from the right to the left, is shown~
The launch process according to the invention 5consists of the following main stages.
Before the launch operation being started, in each of the sections of the pipeline comprised between the manholes, removable separation septa 4 are installed, which subdivide the volume of the pipeline into a 10pLurality of cylindrical volumes 5, each of them having a length about equal to the interval between the manholes.
Said removable septa can be constituted, e.g., b~
balloons to be inflated by pressurized fluids; by blind monolith;c plates, provided at their periphery with a 15toroidal gasket, suitable to be expanded by analogous pressur;zed fluids, having such dimensions that the monolithic plate can easily pass through the manhole; by modular plates, to be so assembled as to form a blind disc, always provided with an expandable toroidal gasket.
20For each cylindrical volume 5 - and, according to a preferred form of practical embodiment of the invention, ~hrough each manhole - two connections equipped witn valves 6 and 7 are provided~ the first of which is connected with a dipleg 11 which reaches the lower 25portion of the cylindrical chamber and is destined to the input and the output of the balLast water; and the second of which is connected with the top of the manhole, and is destined to the inlet and outlet of air.
The so-structured and prearranged pipeline is made 30advance leftwards. While the pipeline section being discussed is still sliding on the mainland, on a suitably prepared path, or is still only partly submerged, the pipeline is preferably left empty from water, to that its resistance to the dragging is very low. Possibly, special guide and support rollers or equivalent means can be S used, to secure a good sliding and prevent the pipeline from being damaged.
In correspondence oF the dipping area of the pipeline being launched, by the connection 6 water is fed, which increases the weight of the subject section 5, 1~ up to the desired valuen From a general viewpoint, such a value may be as high as 250 kg/m , the preferred residual weight range being however of from 10 to 30 kg/m .
Possible excess amounts of ballast water are removed by opening the on-off valve provided on the water connection 6, and feeding, via the connection 7, compressed air~ which expels the desired amount of water, or sucking water from the connection 6.
The launch process according to the invention allows the residual weight of the pipeline to be easily controlled, both over time and in space, and allows thus the pipelines to be laid with higher precisions and a~
faster speeds then of the prior art.
The value of the residual weight to be conferred to the pipeline during the launch depends on the environmental conditions, on its size and on the available draught equipment~
The supply of the required amount of ballast water can be controlled by means of the interposition of volumetric meters, or of equivaLent means, able to supply 3Q a sufficient measurement precision, on the connection 6.
In a specific way, such a measurement precision is required as a function of the tolerances required by the design for the residual weight values.
The launch is carried out on the pipeline, thus brought to the desired value of water we;ght, by applying - 5 a draught action to the offshore end of the same pipeline.
Such a draught can be carried out from 3 pontoon, placed in the nearby of the intake end, suitably anchored and equipped with w;nches. As an alternative, the winches can be installed on the mainland, with an offshore-positioned return.
Once that the launch of the pipeline has ended, the serv;ce equipment is removed from the pipeline.
Such an operation is carried out by skin-divers, serviced by barges.
The operations consist in general of the following steps, for each cylindrical chamber 5:
- complete Filling of the pipeline;
- removal of connections 6 and 7;
- disengament of the cover 10 of the manhole and lifting thereof;
- removal of the dipleg 11, by disconnecting the connection 12;
- application on the fittings 8 and 9, which were formerly connected to the connec~ions 6 and 7, bLind flanges (as an alternative~ said fittings can be removed, and the remaining bores can be closed by screw-threaded plugs);
- disengagement of the separation septum 4;
- recovery of the said separation septum, by passing its components either through the manhole2, or through the 1 0 .
end of the pipeline;
- closure of the manhole 2 again by means of the cover 1 0 ~
The disclosure of the process of the invention has been referred to the typical case of the launch of a pipeline intended for water intake installat;ons for industrial works.
Such a launch process can be advantageously implemented also for launching pipelines through water stretches, for, e~g., crossing water streams, lakes, or sounds, such pipelines being, in any case, assembled on the mainland, and subsequently launched.
The process can be applied as well for crossing not very large water stretches, also w;thout manholes being available. To exemplifying purposes, as the removable septa, inflatable balloons can be used, which are linked in seried to recovery cables; the service connections can be directly applied on the pipeline.
Such a technical solution proves itself suitable, especially for pipelines of smaller dimensions than of those intended for intake installations.
` In order to obviate such drawbacks, according to an improved variant of such a method, float;ng bodies of long shape, placed inside the pipeline, are adopted.
Such a contrivance overcomes the drawbacks characterizing the former variant, but causes notable ;
~ ~ J~
~omplications, bo~h as regards the proper positioning of the floating bodies inside the pipeline, and the procedure for recovering them, at the end of the launch~
During the launching operation9 the buoys used to 5 attain the desired residual weight of the water-filled pipeline, applied both inside the pipeline, and externally to it, are dragged to increasing depths.
This fact leads to a considerable drawback for the buoys constituted by such pneumatic bodies, as balloons or cylinders filled with compressed air, which are the buoys endowed ~ith the best handling and economy of use characteristics.
Such pneumatic bodies, placed at an increasing depth, shrink under the effect due to the increase in the outer pressure; to restore the;r value of positive upwards - buoyancy, such bodies have to be inflated, as the launch being discussed brings them to increasing depths, to the purpose of bringing them back to their initial value.
As an alternative, it is also possible to change the length of the connection between the pipeline being launched and the outer buoys, so to keep these latter at a substantially constant depth.
Both of these solutions result complex.
The adoption of rigid buoys, able to withstand the outer pressurey obliges to resort to rather heavy, poorly handeable metal structures.
Both of ~he procedures of application of the buoys dur;ng the launch, and the procedure for the recovery of the buoys, at ~he end o~ the launch, for them to be used in another site, result complex~
~3~
- 5 ~
The techniques exposed up to here suffer moreover from the drawback tha-t the increase in weight conferred to the pipeline results fixed a priori, and cannot be easily adjusted or modified during the laying, should, e.g., the unevennesses of the bottom, or changes in the ambient conditions, require the residual weight of the whole pipeline, or of a portion thereof, to be changed.
The laying process according to the present invention allows the weight of a pre-assembled pipeline to be increased with precision, to the desired weight value for the pipeline to be launched from the mainland, and said weight to be varied, both over time and along the various sections of the pipeline, as well as said launch to be carried out easily and with economies both of time and of materials.
According to the present invention there is provided a process for the launching of large-size submarine pipelines asse~bled on the mainland and then launched by draught from the water side, characterized in that the launch steps are so arranged:
- subdivision of the inner volume of the pipeline into a plurality of cylindrical volumes, by positioning a plurality of removable separation septa;
- connection of such cylindrical volumes to the outside by means of service connections, at least one of which for the supply and the discharge of ballast water, and at least one for the supply of compressed air inside the top portion of said cylindrical volumes;
- flooding of the cylindrical volumes, normally in correspondence of their dipping into the water stretch wherein the launch is carried out, up to obtain, for the dipped pipeline section, a desired residual weight, the possible ballast excess being expelled by being displaced by ~,"
~, 5a -compressed air;
- con-tinuation and completion of the pipeline launch, by adjusting, by means of the supply or of the discharge of ballast water, the residual weight to be conferred to the pipeline sections already laid in the dep~h;
- completely flooding of the pipeline and removal of the connections and of the separation septa, at the end of the launch.
Such a process of the invention shall be disclosed, by referring to the figure, in the specific application to the lauch of large-size pipelines destined to water intake installations for industrial plants.
However, the following disclosure should not be considered as being limitative of the application scope of the present invention, in that this latter can be used also for large-size pipelines for different uses.
Such pipelines are characterized indeed by very large flowrates, and thus large diameters - up to more than 2,500 mm - as well as by low operating pressure drops, and, consequently, by very limited wall thicknesses - comprised within the range of from 15 to 30 mm - which render such pipelines very dilicate during the launch operations, should they undergo stresses not uniformly distributed lengthwise to ~ ~
.~ _ ..'.~f,.~
According to the coas~al site the water intake units for industrial plants are being installed at, these latter have a length which is usually compr;sed within the range of up to 3 km~ and lay at such a depth as to guarantee the ;ntake of clean water, at a substantially constant temperature during the medium term; and, however, not influenced by the day temperature excursions. According to the site, and the bottoms, such a depth is comprised, in the most frequent cases, within the range of from 10 to 15 metres~
By starting from the intake end, equipped with various grids and protections9 to prevent foreign bodies of discrete dimensions to enter the pipeline, this latter extends up to the mainland, wherein the industrial works are instaLled. In many instances, in the intake unit, in a sea environment, also means are installed for the supply, the metering and the distribution of aclditives to preventr or, at least, limit, the growth of colonies of marine fLora and/or fauna - seaweeds, shellfish and the like - which may occlude the pipeline, even completely, within a short time~ rendering it useless.
The pipelines of the intake installations are provided, at discrete lengths~ with large manholes, whiçh allow skin-divers, provided ~ith aqualungs~ to enter the inner of the pipeline, to period;cally inspec~ the pipeline and eventually service it.
The Length of such sectionsp between the manholes, is generally comprised within the ~ange of from 50 to 120 m, and the manhole has an inner diameter of from 1200 to 1800 mm, which allows the skin divers and their equ;pment to easiiy enter the pipelines.
In the hereto attached figure, the pipeline 1, provided with the manholes 2, which is made advance on the bottom 3, from the right to the left, is shown~
The launch process according to the invention 5consists of the following main stages.
Before the launch operation being started, in each of the sections of the pipeline comprised between the manholes, removable separation septa 4 are installed, which subdivide the volume of the pipeline into a 10pLurality of cylindrical volumes 5, each of them having a length about equal to the interval between the manholes.
Said removable septa can be constituted, e.g., b~
balloons to be inflated by pressurized fluids; by blind monolith;c plates, provided at their periphery with a 15toroidal gasket, suitable to be expanded by analogous pressur;zed fluids, having such dimensions that the monolithic plate can easily pass through the manhole; by modular plates, to be so assembled as to form a blind disc, always provided with an expandable toroidal gasket.
20For each cylindrical volume 5 - and, according to a preferred form of practical embodiment of the invention, ~hrough each manhole - two connections equipped witn valves 6 and 7 are provided~ the first of which is connected with a dipleg 11 which reaches the lower 25portion of the cylindrical chamber and is destined to the input and the output of the balLast water; and the second of which is connected with the top of the manhole, and is destined to the inlet and outlet of air.
The so-structured and prearranged pipeline is made 30advance leftwards. While the pipeline section being discussed is still sliding on the mainland, on a suitably prepared path, or is still only partly submerged, the pipeline is preferably left empty from water, to that its resistance to the dragging is very low. Possibly, special guide and support rollers or equivalent means can be S used, to secure a good sliding and prevent the pipeline from being damaged.
In correspondence oF the dipping area of the pipeline being launched, by the connection 6 water is fed, which increases the weight of the subject section 5, 1~ up to the desired valuen From a general viewpoint, such a value may be as high as 250 kg/m , the preferred residual weight range being however of from 10 to 30 kg/m .
Possible excess amounts of ballast water are removed by opening the on-off valve provided on the water connection 6, and feeding, via the connection 7, compressed air~ which expels the desired amount of water, or sucking water from the connection 6.
The launch process according to the invention allows the residual weight of the pipeline to be easily controlled, both over time and in space, and allows thus the pipelines to be laid with higher precisions and a~
faster speeds then of the prior art.
The value of the residual weight to be conferred to the pipeline during the launch depends on the environmental conditions, on its size and on the available draught equipment~
The supply of the required amount of ballast water can be controlled by means of the interposition of volumetric meters, or of equivaLent means, able to supply 3Q a sufficient measurement precision, on the connection 6.
In a specific way, such a measurement precision is required as a function of the tolerances required by the design for the residual weight values.
The launch is carried out on the pipeline, thus brought to the desired value of water we;ght, by applying - 5 a draught action to the offshore end of the same pipeline.
Such a draught can be carried out from 3 pontoon, placed in the nearby of the intake end, suitably anchored and equipped with w;nches. As an alternative, the winches can be installed on the mainland, with an offshore-positioned return.
Once that the launch of the pipeline has ended, the serv;ce equipment is removed from the pipeline.
Such an operation is carried out by skin-divers, serviced by barges.
The operations consist in general of the following steps, for each cylindrical chamber 5:
- complete Filling of the pipeline;
- removal of connections 6 and 7;
- disengament of the cover 10 of the manhole and lifting thereof;
- removal of the dipleg 11, by disconnecting the connection 12;
- application on the fittings 8 and 9, which were formerly connected to the connec~ions 6 and 7, bLind flanges (as an alternative~ said fittings can be removed, and the remaining bores can be closed by screw-threaded plugs);
- disengagement of the separation septum 4;
- recovery of the said separation septum, by passing its components either through the manhole2, or through the 1 0 .
end of the pipeline;
- closure of the manhole 2 again by means of the cover 1 0 ~
The disclosure of the process of the invention has been referred to the typical case of the launch of a pipeline intended for water intake installat;ons for industrial works.
Such a launch process can be advantageously implemented also for launching pipelines through water stretches, for, e~g., crossing water streams, lakes, or sounds, such pipelines being, in any case, assembled on the mainland, and subsequently launched.
The process can be applied as well for crossing not very large water stretches, also w;thout manholes being available. To exemplifying purposes, as the removable septa, inflatable balloons can be used, which are linked in seried to recovery cables; the service connections can be directly applied on the pipeline.
Such a technical solution proves itself suitable, especially for pipelines of smaller dimensions than of those intended for intake installations.
Claims (6)
1 Process for the launching of large-size submarine pipelines assembled on the mainland and then launched by draught from the water side, characterized in that the launch steps are so arranged:
- subdivision of the inner volume of the pipeline into a plurality of cylindrical volumes, by positioning a plurality of removable separation septa;
- connection of such cylindrical volumes to the outside by means of service connections, at least one of which for the supply and the discharge of ballast water, and at least one for the supply of compressed air inside the top portion of said cylindrical volumes;
- flooding of the cylindrical volumes, normally in correspondence of their dipping into the water stretch wherein the launch is carried out, up to obtain, for the dipped pipeline section, a desired residual weight, the possible ballast excess being expelled by being displaced by compressed air;
- continuation and completion of the pipeline launch, by adjusting, by means of the supply or of the discharge of ballast water, the residual weight to be conferred to the pipeline sections already laid in the depth;
- completely flooding of the pipeline and removal of the connections and of the separation septa, at the end of the launch.
- subdivision of the inner volume of the pipeline into a plurality of cylindrical volumes, by positioning a plurality of removable separation septa;
- connection of such cylindrical volumes to the outside by means of service connections, at least one of which for the supply and the discharge of ballast water, and at least one for the supply of compressed air inside the top portion of said cylindrical volumes;
- flooding of the cylindrical volumes, normally in correspondence of their dipping into the water stretch wherein the launch is carried out, up to obtain, for the dipped pipeline section, a desired residual weight, the possible ballast excess being expelled by being displaced by compressed air;
- continuation and completion of the pipeline launch, by adjusting, by means of the supply or of the discharge of ballast water, the residual weight to be conferred to the pipeline sections already laid in the depth;
- completely flooding of the pipeline and removal of the connections and of the separation septa, at the end of the launch.
2 Process for the launch of large-size submarine pipelines provided with manholes and destined to water intakes according to the preceding claim, characterized in that the separation of the cylindrical volumes is accomplished by installing the separation septa between the said manholes, and executing the service connections in correspondence of the manholes.
3. Process for the launch of large-size pipelines according to claim 1, characterized in that the average residual weight of the pipeline in water is maintained under 250 kg/ m3 and preferably within the range of from 10 to 30 kg / m3.
4. Process for the launch of pipelines according to claim 1, 2 or 3, characterized in that the removable separation septa between the cylindrical volumes are of the expandable type, and are constituted by bodies which are inflated with pressurized fluids, preferably compressed air.
5. Process for the launch of pipelines according to claim 1, 2 or 3, characterized in that the removable separation septa between the cylindrical volumes are of the expandable types, and are constituted by blind plates equipped along their periphery with a toroidal gasket expandable by means of a pressurized fluid, preferably compressed air.
6. Process according to claim 2, characterized in that the service connections for ballast water and compressed air to the cylindrical volumes are provided on the cover of the manhole.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT23129/85A IT1186412B (en) | 1985-12-06 | 1985-12-06 | PROCEDURE FOR LAUNCHING LANDS OF LARGE DIVING CONDUCT FROM THE LAND, ESPECIALLY FOR TAKING WORKS |
| IT23129A/85 | 1985-12-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1263245A true CA1263245A (en) | 1989-11-28 |
Family
ID=11204094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000524676A Expired CA1263245A (en) | 1985-12-06 | 1986-12-05 | Process for the launching from the mainland of large- size submarine pipelines, in particular for intake installations |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4778306A (en) |
| JP (1) | JPS62147186A (en) |
| CN (1) | CN1011529B (en) |
| CA (1) | CA1263245A (en) |
| GB (1) | GB2183776B (en) |
| IN (1) | IN168437B (en) |
| IT (1) | IT1186412B (en) |
| NO (1) | NO864843L (en) |
| SE (1) | SE8605148L (en) |
| SU (1) | SU1530103A3 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO172456C (en) * | 1987-02-03 | 1993-07-21 | Norwegian Contractors | DEVICE AND PROCEDURE FOR RELEASE, BALLAGE AND DEBALLAGE OF PIPE BODIES |
| US4929124A (en) * | 1988-07-28 | 1990-05-29 | Ocean Farms Of Hawaii Limited Partnership | Method and apparatus for constructing and moving long pipelines |
| DE4423815C2 (en) * | 1994-07-06 | 1996-09-26 | Loesche Gmbh | Mill classifier |
| US5294214A (en) * | 1992-05-29 | 1994-03-15 | Union Oil Company Of California | Gas eliminator for offshore oil transfer pipelines |
| US5899635A (en) * | 1997-05-09 | 1999-05-04 | Kuja; Michael W. | Transportation underwater tunnel system |
| DE19954430A1 (en) * | 1999-11-11 | 2001-05-31 | Karl Heinz Krah Gmbh Werkzeug | Procedure for laying pipelines in the sea or in larger inland waters |
| ES2231088T3 (en) | 2000-02-02 | 2005-05-16 | Distec Gmbh | POSTER SUSPENSION DEVICE. |
| GB0109049D0 (en) * | 2001-04-11 | 2001-05-30 | Psl Technology Ltd | Method |
| JP4739606B2 (en) * | 2001-08-28 | 2011-08-03 | 大成建設株式会社 | Structure of submerged piping |
| US7155848B2 (en) | 2003-06-05 | 2007-01-02 | 501413 Ontario Limited | Apparatus for a scrolling sign |
| US8226328B2 (en) * | 2008-09-03 | 2012-07-24 | Fairfield Industries Incorporated | Seismic cable with adjustable buoyancy |
| CN102162555B (en) * | 2011-04-12 | 2013-01-02 | 中国十九冶集团有限公司 | Method for laying ore pulp pipeline in marsh district |
| CN103590421B (en) * | 2013-11-07 | 2015-08-19 | 浙江海洋学院 | Off-shore pipeline anti-aging storage method and beach off-shore pipeline anti-aging store the pool |
| CN103899842B (en) * | 2014-04-23 | 2017-01-11 | 中国海洋石油总公司 | Method for installing deepwater online tee joint |
| US9797525B2 (en) * | 2014-05-29 | 2017-10-24 | Ecosse Subsea Systems, Ltd. | Method of governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid |
| FR3028912B1 (en) * | 2014-11-20 | 2016-12-30 | Technip France | METHOD FOR PLACING A FLEXIBLE LINE COMPRISING AN EXTERNAL SHEATH DELIMINATING AN INTERNAL VOLUME AND FLEXIBLE LINE ASSOCIATED THEREWITH |
| CN104613234B (en) * | 2015-01-15 | 2016-08-24 | 中国海洋石油总公司 | The recovery method of deepwater pipelines pipe abandon |
| CN106167229B (en) * | 2016-06-21 | 2018-06-08 | 中交天航港湾建设工程有限公司 | A kind of construction method of the underwater pipeline of dredging of marine lifting |
| GB2574586B (en) * | 2018-06-05 | 2021-06-23 | Subsea 7 Ltd | Connecting multi-bore structures in water |
| GB2620371A (en) | 2022-06-28 | 2024-01-10 | Subsea 7 Norway As | Assembly, transportation and installation of floating wind turbines |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US30825A (en) * | 1860-12-04 | johnson | ||
| US2731800A (en) * | 1956-01-24 | collins | ||
| US650134A (en) * | 1900-01-09 | 1900-05-22 | Hiram W Phillips | Apparatus for submarine pipe-laying. |
| US2807937A (en) * | 1954-07-15 | 1957-10-01 | Macco Corp | Subaqueous pipeline bulkhead construction |
| US3487648A (en) * | 1965-05-21 | 1970-01-06 | Brown & Root | Methods for laying pipelines |
| US3479831A (en) * | 1967-09-20 | 1969-11-25 | Columbia Gas Syst | Method and system for laying pipe under water |
| US3583169A (en) * | 1969-07-08 | 1971-06-08 | North American Rockwell | Submarine pipeline laying |
| US3756034A (en) * | 1972-04-04 | 1973-09-04 | Brown & Root | Method and apparatus for laying pipelines |
| US3890693A (en) * | 1972-10-26 | 1975-06-24 | Harold N Eagleton | Method for controlled pressurization of a pipeline during construction thereof |
| US3977201A (en) * | 1975-03-19 | 1976-08-31 | Bittner Robert B | Method and apparatus for preventing buckling of pipeline as it is being assembled and laid on the ocean floor |
| US4104886A (en) * | 1976-05-31 | 1978-08-08 | Compagnie Generale Pour Les Developpements Operationnels Des Richesses Sous-Marines "C. G. Doris" | Float for use in laying submarine pipelines |
| ATE19146T1 (en) * | 1980-10-17 | 1986-04-15 | Wolfgang Dipl Ing Zeilinger | METHOD OF LAYING PIPELINES IN WATER. |
| US4360290A (en) * | 1980-12-17 | 1982-11-23 | Shell Oil Company | Internal pipeline plug for deep subsea pipe-to-pipe pull-in connection operations |
-
1985
- 1985-12-06 IT IT23129/85A patent/IT1186412B/en active
-
1986
- 1986-12-01 SE SE8605148A patent/SE8605148L/en not_active Application Discontinuation
- 1986-12-01 IN IN925/MAS/86A patent/IN168437B/en unknown
- 1986-12-02 NO NO864843A patent/NO864843L/en unknown
- 1986-12-05 US US06/938,602 patent/US4778306A/en not_active Expired - Fee Related
- 1986-12-05 JP JP61289088A patent/JPS62147186A/en active Pending
- 1986-12-05 SU SU864028666A patent/SU1530103A3/en active
- 1986-12-05 GB GB8629134A patent/GB2183776B/en not_active Expired
- 1986-12-05 CA CA000524676A patent/CA1263245A/en not_active Expired
- 1986-12-06 CN CN86108852A patent/CN1011529B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN86108852A (en) | 1987-10-28 |
| GB2183776A (en) | 1987-06-10 |
| CN1011529B (en) | 1991-02-06 |
| SU1530103A3 (en) | 1989-12-15 |
| JPS62147186A (en) | 1987-07-01 |
| SE8605148D0 (en) | 1986-12-01 |
| IT8523129A0 (en) | 1985-12-06 |
| GB2183776B (en) | 1989-10-11 |
| US4778306A (en) | 1988-10-18 |
| IT1186412B (en) | 1987-11-26 |
| NO864843D0 (en) | 1986-12-02 |
| SE8605148L (en) | 1987-06-07 |
| NO864843L (en) | 1987-06-09 |
| IN168437B (en) | 1991-04-06 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |